Mesogenic cyanate functional maleimides and thermosets thereof

ABSTRACT

Compounds containing at least one cyanate group, at least one maleimide group and at least one rodlike mesogenic moiety are prepared by reacting one or more aminophenols containing one or more rodlike mesogenic moieties with a stoichiometric quantity of a maleic anhydride per amine group of said aminophenol and then cyanating the resulting phenolic functional maleimide.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.07/730,403 filed Jul. 16, 1991 (now abandoned) which is a division ofapplication Ser. No. 07/596,138 filed Oct. 11, 1990 (now U.S. Pat. No.5,077,380 issued Dec. 31, 1991) which is is a continuation-in-part ofapplication Ser. No. 07/380,936 filed Jul. 17, 1989 (now abandoned) allof which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention concerns cyanate functional maleimides containingone or more rodlike mesogenic moieties.

BACKGROUND OF THE INVENTION

Copolymerization products of compounds containing two or more cyanategroups with compounds containing two or more maleimide groups are known,for example, from U.S. Pat. Nos. 4,110,364; 4,287,014; 4,369,304;4,370,467; 4,371,689; 4,373,086; 4,383,903; 4,393,195; 4,396,745;4,404,330 and 4,469,859. Representative of said copolymerizationproducts is the bismaleimide-triazine resin prepared by copolymerizationof bisphenol A dicyanate and N,N'-(methylene-di-phenylene)bismaleimide.Preparation of said copolymerization products always requires premixingor contacting together two separate components: the polycyanate compoundand the polymaleimide compound.

Hefner, Jr. in U.S. Pat. Nos. 4,680,378; 4,683,276; 4,731,426 and4,769,440 provides novel compositions which simultaneously contain botha cyanate group and a maleimide group. Thus, said compositions avoid thepremixing or contacting together of separate polycyanate and maleimidecomponents to provide products containing cyanate group and maleimidegroup copolymerization structures.

The novel compositions of the present invention also simultaneouslycontain both a cyanate group and a maleimide group but additionallycontain one or more rodlike mesogenic moieties. The presence of one ormore rodlike mesogenic moieties serves to improve one or more physicalor mechanical properties of the cured compositions relative to the curedcompositions prepared using the cyanate functional maleimides of theprior art.

SUMMARY OF THE INVENTION

The present invention pertains to cyanate functional maleimidecompositions containing one or more rodlike mesogenic moieties,particularly those represented by the following Formulas I, II, III orIV ##STR1## wherein at least about 80 percent of the --A-- linkages inFormulas I, II and IV and the direct bond in Formula III and the Ygroups are in the para position with respect to each other; one Y groupis a cyanate, --O--C.tbd.N, group and the other Y group is a maleimidegroup represented by the formula ##STR2## each A is independently --CR¹═CR¹ --, --C.tbd.C--, --N═N--, --CR¹ ═N--, --O--CO--, --NR¹ --CO--,--CR¹ ═N--N═CR¹ --, --CR¹ ═CR¹ --CO--, --CO--O--, --CO--NR¹ --,--CO--CR¹ ═CR¹ --, --CR¹ ═CR¹ --O--CO--(CH₂)_(n') --, --N═CR¹ --,--(CH₂)_(n') --CO--O--CR¹ ═CR¹ --, --CR¹ --CR¹ --O--CO--, --CO--O--CR¹═CR¹ --, --CO--O--N═CR¹ --, --CR¹ ═N--O--CO--, --CR¹ ═CR¹ --CO--O--,--CO--S--, --O--CO--CR¹ ═CR¹ --, --CR¹ ═CR¹ --CO--O--(CH₂)_(n') --,--S--CO--, --(CH₂)_(n') --O--CO--CR¹ ═CR¹ --, --CHR¹ --CHR¹ --CO--O--,--O--CO--CHR¹ --CHR¹ --, --C.tbd.C--C.tbd.C--, --CR¹ ═CR¹ --CR¹ ═CR¹ --,--CO--NR¹ --NR¹ --CO--, ##STR3## A' is a divalent hydrocarbyl grouphaving from 1 to about 10, preferably from 1 to about 4, carbon atoms;each A" is independently an alkylene group having from 1 to about 10carbon atoms, preferably from 1 to about 4 carbon atoms, a direct bond,--O--, --CO--, --S--, --S--S--, --SO--, --SO₂ -- or --O--CO--O--; eachA¹ is independently a --CO--, --O--CO--, --CO--O--, --CO--NR¹ --, or--NR¹ --CO-- group; each R is independently hydrogen or a hydrocarbyl orhydrocarbyloxy group having from 1 to about 10, preferably from 1 toabout 4. carbon atoms, a halogen atom, preferably chlorine or bromine, anitro group, a nitrile group, a phenyl group or a --CO--R¹ group; eachR¹ is independently hydrogen or a hydrocarbyl group having 1 to about 3carbon atoms; n has a value of zero or one; n' has an average value fromzero to about 6, preferably zero to about 3; and p has an average valuefrom 1 to about 30, preferably from 1 to about 3. The aromatic rings canalso contain one or more heteroatoms selected from N, O, S and the like.

Another aspect of the present invention pertains to compositionsresulting from curing (thermosetting) one or more of the cyanatefunctional maleimides containing one or more rodlike mesogenic moieties,optionally in the presence of one or more curing agents or curingcatalysts.

Another aspect of the present invention is directed to polymerizablecompositions comprising a mixture containing

(A) at least one thermosettable cyanate functional maleimide containingone or more rodlike mesogenic moieties; and

(B) at least one of

(1) at least one polycyanate or polycyanamide which does not containrodlike mesogenic structures;

(2) at least one epoxy resin;

(3) at least one polymaleimide;

(4) at least one polyamine;

(5) at least one polyphenol;

(6) at least one compound containing one or more polymerizableethylenically unsaturated group(s);

(7) at least one compound which contains in the same molecule both acyanate or cyanamide group and a polymerizable ethylenically unsaturatedgroup;

(8) at least one compound which contains in the same molecule both a1,2-epoxide group and a polymerizable ethylenically unsaturated group;

(9) at least one compound which contains in the same molecule both amaleimide group and a cyanate group and does not contain rodlikemesogenic structures;

(10) at least one compound which contains one or more rodlike mesogenicmoieties and only one cyanate or cyanamide group per molecule;

(11) at least one prepolymer of any of the aforesaid components (1)through (10) or any combination of any two or more of said components;or

(12) a mixture of any two or more of components (1) through (11) in anyproportion and any combination.

Another aspect of the present invention pertains to compositionsresulting from polymerizing the aforementioned polymerizablecompositions.

A further aspect of the present invention pertains to products resultingfrom orienting any of the aforementioned polymerizable compositions.

The term prepolymers as employed herein means that the compound has beenhomooligomerized or cooligomerized or interoligomerized orhomopolymerized or copolymerized or interpolymerized so as to cause anincrease in molecular weight, but not to such an extent that the producthas become cured, i.e. insoluble and infusible, but rather, the productis capable of being subsequently cured to an insoluble, infusible state.

DETAILED DESCRIPTION OF THE INVENTION Preparation of the CyanateFunctional Maleimides Containing One or More Rodlike Mesogenic Moieties

The cyanate functional maleimides of the present invention are preparedby reacting one or more aminophenols containing one or more rodlikemesogenic moieties with a stoichiometric quantity of a maleic anhydrideper amine group of said aminophenol in the presence of a suitablesolvent and then cyanating the resulting phenolic functional maleimide.

Suitable aminophenols which can be employed herein to prepare thecyanate functional maleimides containing one or more rodlike mesogenicmoieties include, for example, any compound which has an average of onearomatic hydroxyl group and aromatic primary amino group per moleculeand include, for example, those represented by the Formulas V, VI, VIIor VIII ##STR4## wherein at least about 80 percent of the --A-- linkagesin Formulas V, VI and VIII and the direct bond between the two aromaticrings in Formula VII and the Y¹ groups are in the para position withrespect to each other; one Y¹ group is --OH and the other is --NH₂ ;each A, A', A", A¹ , R, R¹, n, n' and p are as hereinbefore defined. Thearomatic rings can also contain one or more heteroatoms selected from N,O, S and the like.

The term hydrocarbyl as employed herein means any aliphatic,cycloaliphatic, aromatic, aryl substituted aliphatic or cycloaliphatic,or aliphatic or cycloaliphatic substituted aromatic group. The aliphaticor cycloaliphatic groups can be saturated or unsaturated. When appliedto the A' group of Formulas III and VII, the hydrocarbyl group can alsocontain one or more heteroatoms selected from N, O, S and the like.Likewise, the term hydrocarbyloxy means a hydrocarbyl group having anoxygen linkage between it and the carbon atom to which it is attached.

Particularly suitable aminophenols are, for example, ##STR5## mixturesthereof and the like.

Suitable maleic anhydrides include, for example, those represented bythe Formula IX ##STR6## wherein R¹ is as hereinbefore defined. Suitablemaleic anhydrides include maleic anhydride, methyl maleic anhydride,mixtures thereof and the like. Most preferred as the maleic anhydride ismaleic anhydride per se.

Suitable solvents include aliphatic monocarboxylic acids such as aceticacid, propionic acid, mixtures thereof and the like. Most preferred asthe solvent is acetic acid. The maleamic acid resulting from reaction ofa maleic anhydride and an amionphenol compound, typically in an inertsolvent such as chloroform, toluene or dioxane, may be isolated thendehydrated in an aliphatic monocarboxylic acid to the correspondingphenolic functional maleimide. Alternately, the reaction may beperformed in a single continuous step in the aliphatic monocarboxylicacid solvent. The product resulting from this reaction is a phenolicfunctional maleimide represented by the Formulas X, XI, XII and XIII##STR7## wherein R, R¹, A, A', A", A¹, n, n' and p are as hereinbeforedefined.

Cyanate functional maleimide compositions containing one or more rodlikemesogenic moieties are conveniently prepared by reacting astoichiometric quantity up to a slight stoichiometric excess (up toabout 20 percent excess) of a cyanogen halide with a phenolic functionalmaleimide containing one or more rodlike mesogenic moieties, such asthose represented by Formulas X, XI, XII and XIII, in the presence of astoichiometric quantity of a base material.

Suitable cyanogen halides include cyanogen chloride and cyanogenbromide. Alternately, the method of Martin and Bauer described inOrganic Synthesis, volume 61, pages 35-68 (1983) published by John Wileyand Sons, which is incorporated herein by reference, can be used togenerate the required cyanogen halide in situ from sodium cyanide and ahalogen such as chlorine or bromine.

Suitable base compounds include both inorganic bases and tertiary aminessuch as sodium hydroxide, potassium hydroxide, trimethylamine,triethylamine, mixtures thereof, and the like. Triethylamine is mostpreferred as the base.

Suitable solvents for the cyanation reaction include water, aliphaticketones, chlorinated hydrocarbons, aliphatic and cycloaliphatic ethersand diethers, aromatic hydrocarbons, mixtures thereof and the like.Acetone, methylethylketone, methylene chloride or chloroform areparticularly suitable as the solvent. Reaction temperatures of fromabout -40° C. to about 60° C. are operable, with reaction temperaturesof -15° C. to 10° C. being preferred. Reaction times can varysubstantially, for example, as a function of the reactants beingemployed, the reaction temperature, solvent(s) used, the scale of thereaction, and the like, but are generally between 15 minutes and 4hours. with reaction times of 30 minutes to 90 minutes being preferred.

Curing of the Cyanate Functional Maleimides Containing One or MoreRodlike Mesogenic Moieties

The cyanate functional maleimides containing one or more rodlikemesogenic structure(s) are cured (thermoset) by heating from about 50°C. to about 400° C., preferably by heating from 100° C. to 250° C.,optionally in the presence of a suitable catalyst. Suitable catalystsinclude, for example, acids, bases, salts, free radical formingmaterials, nitrogen and phosphorus compounds, such as for example, Lewisacids such as AlCl₃, BF₃, FeCl₃, TiCl₄, ZnCl₂, SnCl₄ ; protonic acidssuch as HCl, H₃ PO₄ ; aromatic hydroxy compounds such as phenol,p-nitrophenol, pyrocatechol, dihydroxynaphthalene; organic peroxides andhydroperoxides such as t-butylperoxybenzoate, benzoyl peroxide,t-butylhydroperoxide; azo and diazo compounds such asazobisisobutyronitrile; sodium hydroxide, sodium methylate, sodiumphenolate, trimethylamine. triethylamine, tributylamine,diazabicyclo-[2.2.2]-octane, quinoline, isoquinoline,tetrahydroisoquinoline, tetraethylammonium chloride, pyridine-N-oxide,tributyl phosphine, zinc octoate, tin octoate, zinc naphthenate, cobaltnaphthenate, cobalt octoate, cobalt acetylacetonate and the like. Alsosuitable as catalysts are the metal chelates such as, for example, thechelates of transition metals and bidentate or tridentate ligands,particularly the chelates of iron, cobalt, zinc, copper, manganese,zirconium, titanium, vanadium, aluminum and magnesium. These and otheroperable catalysts are disclosed in U.S. Pat. Nos. 3,694,410 and4,094,852 which are incorporated herein by reference in their entirety.Cobalt naphthenate, cobalt octoate and cobalt acetylacetonate are mostpreferred as the catalysts. The quantity of catalyst used, if any,depends on the structure of the particular catalyst, the structure ofthe cyanate functional maleimide being cured, the cure temperature, thecure time, and the like. Generally, catalyst concentrations of fromabout 0.001 to about 2 percent by weight are preferred.

B-staging or prepolymerization of the compositions of the cyanatefunctional maleimides of the present invention can be accomplished byusing lower temperatures and/or shorter curing times. Curing of the thusformed B-staged (prepolymerized) resin can then be accomplished at alater time or immediately following B-staging (prepolymerization) byincreasing the temperature and/or curing time.

The cured (thermoset) products prepared from the cyanate functionalmaleimides containing rodlike mesogenic structure(s) possess a complexvariety of curing structures including the cyanate grouphomopolymerization structure ##STR8## the maleimide grouphomopolymerization structure ##STR9## and cyanate group and maleimidegroup copolymerization structures such as, for example, ##STR10## unlessother functionalities are present in the polycyanate that participate inthe curing process.

Polycyanates or Polycyanamides which do not Contain Rodlike esogenicMoieties and which can be Employed in the Curable and Cured Compositions

Suitable polycyanates or polycyanamides which do not contain rodlikemesogenic structures and which can be employed to prepare thepolymerizable mixtures of the present invention include, for example,those represented by the following Formulas XIV, XV, XVI and XVII##STR11## wherein A" and n are as hereinbefore defined; each Y² is a--O--C.tbd.N or a --NR¹ --C.tbd.N group; each A² is independently analkylene group having from 1 to about 10, preferably from 1 to about 4carbon atoms or a ##STR12## each R' is independently hydrogen, ahydrocarbyl or hydrocarbyloxy group having from 1 to about 10,preferably 1 to about 4 carbon atoms, a halogen, preferably chlorine orbromine, a phenyl group, a --O---C.tbd.N group, or a --NR¹ --C.tbd.Ngroup; each R" is independently hydrogen, a hydrocarbyl orhydrocarbyloxy group having from 1 to about 10, preferably 1 to about 4carbon atoms, a halogen, preferably chlorine or bromine, or a phenylgroup; p' has a value from zero to about 100, preferably from zero toabout 30; p" has a value of from zero to about 10, preferably from zeroto 3 and m has a value of from about 0.001 to about 6, preferably fromabout 0.01 to about 3. The aromatic rings can also contain one or moreheteroatoms selected from N, O, S and the like.

Suitable polycyanates or polycyanamides which do not contain rodlikemesogenic structures represented by Formulas XIV, XV, XVI and XVIIinclude, for example, bisphenol A dicyanate, the dicyanates of4,4'-dihydroxydiphenyl oxide, resorcinol, hydroquinone,4,4'-thiodiphenol, 4,4'-sulfonyldiphenol, 3,3',5,5'-tetrabromobisphenolA, 2,2',6,6'-tetrabromobisphenol A, 2,2'-dihydroxydiphenyl,3,3'-dimethoxybisphenol A, 4,4'-dihydroxydiphenylcarbonate,dicyclopentadiene diphenol, 4,4'-dihydroxybenzophenone,4,4'-dihydroxydiphenyl methane, tricyclopentadiene diphenol, thetricyanate of tris(hydroxyphenyl)methane, the tetracyanate of2,2',4,4'-tetrahydroxydiphenyl methane, the polycyanate of aphenolformaldehyde condensation product (novolac), the polycyanate of adicyclopentadiene and phenol condensation product, the dicyanamide of4,4'-diaminodiphenyl methane, the cyanate cyanamide of p-aminophenol,and the like.

The polycyanates or polycyanamides which do not contain rodlikemesogenic structures are prepared using the corresponding polyphenol,polyamine or aminophenol precursor and the previously describedcyanation (cyanamidation) chemistry.

Epoxy Resins which can be Employed in the Curable and Cured Compositions

Suitable epoxy resins which can be employed to prepare the polymerizablemixtures of the present invention include materials having an average ofmore than one vicinal epoxide group per molecule, such as, for example,the epoxy resins represented by the following Formulas XVIII, XIX, XX,XXI, XXII, XXIII, XXIV, XXV, XXVI, XXVII ##STR13## wherein A, A², A',A", R, R.sup., R", m and n are as hereinbefore defined; each R² isindependently hydrogen, or a hydrocarbyl or halohydrocarbyl group havingfrom 1 to about 6, preferably 1 to about 2 carbon atoms; Q is a directbond, --CH₂ --S--CH₂ --, --(CH₂)_(n") --, or ##STR14## m' has a value offrom zero to about 30, preferably from about zero to about 5; m" has avalue from 1 to about 10, preferably from about 1 to about 4 and n" hasan average value from about 1 to about 10. The aromatic rings can alsocontain one or more heteroatoms selected from N, O, S and the like.

Particularly suitable epoxy resins represented by Formulas XXVIII, XIX,XX, XXI, XXII, XXIII, XXIV, XXV, XXVI and XXVII are the diglycidylethers of resorcinol, hydroquinone, dihydroxydiphenyl methane, bisphenolA, 3,3',5,5'-tetrabromobisphenol A, 4,4'-sulfonyldiphenol,4,4'-thiodiphenol, 4,4'-dihydroxydiphenyl oxide,4,4'-dihydroxybenzophenone, 2,2'-dihydroxydiphenyl, dicyclopentadienediphenol, tricyclopentadiene diphenol, 4,4'-dihydroxydiphenyl,4,4'-dihydroxystilbene, 4,4'-dihydroxy-alpha-methylstilbene,4,4'-dihydroxy-alpha-cyanostilbene, 4,4'-dihydroxychalcone,4,4'-dihydroxydiphenylacetylene, 4,4'-dihydroxydiphenylazomeshine,4,4'-hydroxyazobenzene, 4,4'-bis(4-hydroxyphenoxy)diphenyl,4,4'-dihydroxybenzanilide, ethylene glycol, thiodiglycol, diethyleneglycol, dipropylene glycol, polypropylene glycol, polyethylene glycol,1,4-cyclohexanediol, dibutylene glycol, the advancement reaction productof the diglycidyl ether of bisphenol A and bisphenol A, the advancementreaction product of the diglycidyl ether of4,4'-dihydroxy-alpha-methylstilbene and4,4'-dihydroxy-alpha-methylstilbene, the triepoxide of p-aminophenol,the tetraepoxide of 4,4'-diaminodiphenyl methane, the triglycidyl etherof tris(hydroxyphenyl)methane, the tetraglycidyl ether of2,2',4,4'-tetrahydroxydiphenyl methane, the polyglycidyl ether of aphenolformaldehyde condensation product (novolac), the polyglycidylether of a dicyclopentadiene or oligomer thereof and phenol or halogenor alkyl substituted phenol condensation product and the like.

The aforementioned epoxy resins can be prepared by reaction of apolyphenol (polyamine, aminophenol, polyalkylene glycol) with anepihalohydrin and a basic acting material. Said reaction generallyinvolves two distinct steps: coupling reaction of the epihalohydrin andpolyphenol to provide a halohydrin intermediate and dehydrohalogenationreaction of the halohydrin intermediate to provide the glycidyl etherproduct. Suitable catalysys and reaction conditions for preparing epoxyresins are described in the Handbook of Epoxy Resins by Lee and Neville,McGraw-Hill (1967) which is incorporated herein by reference.

Polymaleimides for Use in the Curable and Cured Compositions

Suitable polymaleimides which can be employed to prepare thepolymerizable mixtures of the present invention include, for example,those represented by the Formulas XXVIII, XXIX, XXX, XXXI, XXXII,XXXIII, XXXIV and XXXV ##STR15## wherein A, A², A', A", R, R¹, R", m, nand p are as hereinbefore defined and Q' is a divalent hydrocarbyl grouphaving from 2 to about 12 carbon atoms and may be linear or branchedaliphatic, cycloaliphatic or polycycloaliphatic. The aromatic rings canalso contain one or more heteroatoms selected from N, O, S and the like.

Particularly suitable polymaleimides represented by Formulas XXVIII,XXIX, XXX. XXXI, XXXII, XXXIII, XXXIV and XXXV areN,N'-ethylenebismaleimide, N,N'-ethylenebis(2-methylmaleimide),N,N'-hexamethylenebismaleimide, N,N'-(oxydi-p-phenylene)bismaleimide,N,N'-(methylenedi-p-phenylene)maleimide,N,N'-(methylenedi-p-phenylene)bis(2-methylmaleimide),N,N'-(thio-di-p-phenylene)bismaleimide,N,N'-(sulfonyldi-m-phenylene)bismaleimide,N,N'-(isopropylidenedi-p-phenylene)bismaleimide, polymethylenepolyphenylene polymaleimides, the bismaleimide of 4,4'-diaminostilbene,the bismaleimide of 4,4'-diaminobenzanilide and the like.

The polymaleimides can be prepared by reacting a stoichiometric quantityof a maleic anhydride per amine group with a polyamine in the presenceof a suitable solvent, such as, for example, aromatic hydrocarbons,chlorinated hydrocarbons or N,N-dimethylformamide. The polymaleamic acidresulting from reaction of a maleic anhydride and a polyamine may beisolated and dehydrated to the desired polymaleimide. Alternately, thereaction may be performed in a single continuous step. Detailedprocedures for preparing polymaleimide3 can be found in U.S. Pat. Nos.2,444,536; 2,462,835; and Journal of Polymer Science: Part A: PolymerChemistry, Vol. 27, pages 375-388 (1989) which are incorporated hereinby reference.

Polyamines Suitable for Use in the Curable and Cured Compositions

Suitable polyamines which can be employed to prepare the polymerizablemixtures of the present invention, include those containing one or moreof the rodlike mesogenic structure(s) already described herein, as wellas any of the other known polyamines which do not contain rodlikemesogenic structures. Typical representatives of said polyamines free ofrodlike mesogenic structures include 1,4-diaminobutane,1,6-hexanediamine, 1,12-diaminododecane,2-methyl-4-ethyl-1,8-diaminooetane, 1,4-diamino-cyclohexane,4,4'-diaminodiphenyl methane, 1,4-diaminobenzene,tris(aminophenyl)methane, anilineformaldehyde condensation products andthe like.

Polyphenols Suitable for Use in the Curable and Cured Compositions

Suitable polyphenols which can be employed to prepare the polymerizablemixtures of the present invention, include those containing one or moreof the rodlike mesogenic structure(s) already described herein as wellas any of the other known polyphenols which do not contain rodlikemesogenic structures. Typical representatives of said polyphenols freeof rodlike mesogenic structures include resorcinol,4,4'-sulfonyldiphenol, 4,4'-dihydroxydiphenyl oxide,tris(hydroxyphenyl)methane, phenolformaldehyde condensation products andthe like.

Polymerizable Unsaturated Monomers Suitable for Use in the Curable andCured Compositions

Suitable compounds containing one or more polymerizable ethylenicallyunsaturated group(s) which can be employed to prepare the polymerizablemixtures of the present invention include both those containing one ormore rodlike mesogenic structure(s) and those free of said structures.

Suitable polymerizable ethylenically unsaturated monomers containing oneor more rodlike mesogenic moieties are cataloged by Alexandre Blumsteinin Liquid Crystalline Order in Polymers, published by Academic Press,New York (1978) on pages 105-140; Mesomorphic Order in Polymers andPolymerization in Liquid Crystalline Media published by AmericanChemical Society (ACS Symposium Series 74), Washington, D.C. (1978) onpages 56-70; and N. A. Plate and V. P. Shibaev in Comb-Shaped Polymersand Liquid Crystals published by Plenum Press, New York (1987) on pages1-415; V. Percec, et. al., Polymer Bulletin, 17, pages 347-352 (1987);R. Duran and P. Gramain, Makromol. Chem., 188, pages 2001-2009 (1987);A. M. Mousa, et. al., Polymer Bulletin, 6, pages 485-492 (1982); H.Finkelmann, et. al., Makromol. Chem., 179, pages 829-832 (1978); M.Portugall, et. al., Makromol. Chem., 183, pages 2311-2321 (1982) andU.S. Pat. Nos. 4,637,896 and 4,614,619, all of which are incorporatedherein by reference. Suitable polymerizable ethylenically unsaturatedmonomers containing one or more rodlike mesogenic moieties per moleculeare represented by the Formulas XXXVI or XXXVII:

    M--Q.sup.2                                                 FORMULA XXXVI

    M--(Q.sup.3).sub.n --R.sup.3 --Q.sup.2                     FORMULA XXXVII

wherein n and R¹ are as hereinbefore defined, M is a group containingtwo or more aromatic rings bridged by a rigid central linkage, R³ is adivalent hydrocarbon group having from one to about 12 carbon atoms andmay be linear, branched, cyclic, aromatic or a combination thereof andmay be substituted with one or more inert groups, such as, for example,a methoxy group, or may contain one or more inert heteroatom containinglinkages, such as, for example, an ether linkage; Q³ is --O--, --NR¹ --,--S--, --O--CO--, --CO--O--, --NR¹ --CO--, --CO--NR¹ --, --CO--,--O--CO--O--, --S--CO--, --CO--S--, --NR¹ --CO--O--, --O--CO--NR¹ --,--NR¹ --CO--NR¹ --; and Q² is a polymerizable ethylenically unsaturatedgroup. As a class, these monomers generally contain a --CH=CH₂, allyl,methallyl, propenyl, isopropenyl, acrylate or methacrylate group as thepolymerizable ethylenically unsaturated group and a linear divalentaliphatic, aliphatic ether, aliphatic polyether, aliphatic thioether orcycloaliphatic flexible spacer connecting the polymerizableethylenically unsaturated group and the rodlike mesogenic group(s)through a heteroatom linkage. Typical rodlike mesogenic groups includethose wherein two or more aromatic rings are bridged by a rigid centrallinkage wherein said rigid central linkage is required to bridge thearomatic rings to provide at least about 80 percent para substitution.The aromatic rings can be inertly substituted, however, unsubstitutedaromatic rings which maximize the molecular aspect ratio are preferred.Also preferred is a single inert substituent in the para position on thering not connected to the polymerizable ethylenically unsaturated group(either directly or via a flexible spacer). This type of substituent canbe used to enhance the molecular aspect ratio. Typical of these inertsubstituents are CH₃ O--, Cl--, NO₂ --, --C.tbd.N and the like. Thearomatic rings can also contain one or more heteroatoms selected from N,O, S and the like. Typical rigid central linkage groups for bridging thearomatic rings include, for example, a direct bond, --CR¹ ═CR¹ --,--C.tbd.--C--, --N═N--, --CR¹ ═N--, --CR¹ ═N--N═CR¹ --, --CR¹ ═CR¹--CO--, --O--CO--, --NR¹ --CO--, --CO--O--, --CO--NR¹ --, --CO--CR¹ ═CR¹--, --CR¹ ═CR¹ --O--CO--(CH₂)_(n') --, --N═CR¹ --, --(CH₂)_(n')--CO--O--CR¹ ═CR¹ --, --CR¹ ═CR¹ --O--CO--, --CO--O--CR¹ ═CR¹ --,--CO--O--N═CR¹ --, --CR¹ ═N--O--CO--, --CR¹ ═CR¹ --CO--O--, --CO--S--,--O--CO--CR¹ ═CR¹ --, --CR¹ ═CR¹ --CO--O--(CH₂)_(n') --, --S--CO--,--(CH₂)_(n') --O--CO--CR¹ ═CR¹ --, --CHR¹ --CHR¹ --CO--O--,--O--CO--CHR¹ --CHR¹ --, --C.tbd.--C--C.tbd.--C--, --CR¹ ═CR¹ --CR¹ ═CR¹--, --CO--NR¹ --NR¹ --CO--, ##STR16## and the like; wherein R¹, A¹, nand n' are as hereinbefore defined. As is well known in the prior art,all or a part of the aromatic rings can be replaced with otherpromesogenic structures, such as, for example, the trans-cyclohexanering or a cholesterol group. Additionally, it is has been demonstratedin the prior art that efficacious rodlike mesogen containingpolymerizable ethylenically unsaturated monomers can be prepared withomission of the flexible spacer between the polymerizable ethylenicallyunsaturated group and the rodlike mesogenic group(s).

Generally, the ethylenically unsaturated monomers containing --CH═CH₂,acrylate, allyl, methallyl, propenyl, isopropenyl or methacrylate as thepolymerizable vinyl group and a linear divalent hydrocarbon groupconnecting the vinyl group and the rodlike mesogenic group throughheteroatom containing functional groups between the hydrocarbon spacerand the mesogenic group are most preferred. Thus, a mesogenic groupether linked to a --CH₂ --CH₂ -- which is in turn linked to provide amethacrylate ester, that is, ##STR17## or a mesogenic group linked to avinyl group, that is, ##STR18## are examples of those species preferredas the ethylenically unsaturated monomer containing one or more rodlikemesogenic moieties.

Particularly suitable ethylenically unsaturated monomers containing arodlike mesogenic moiety include, for example, ##STR19## any combinationthereof and the like.

Suitable polymerizable ethylenically unsaturated monomers which do notcontain rodlike mesogenic structures can be selected from the many knownclasses of polymerizable vinyl monomers. Suitable such monomers include,for example, the vinyl aromatic compounds represented by the followingFormula XXXVIII ##STR20## wherein each R¹ is as hereinbefore defined, Y³is independently hydrogen, a hydrocarbyl or hydrocarbyloxy group havingfrom 1 to about 5 carbon atoms, a vinyl group, an allyl group, amethallyl group, a propenyl group, a isopropenyl group, a nitro group, anitrile group, a halogen, such as chlorine or bromine or fluorine, or a--CO--R¹ group; each Y⁴ is independently hydrogen, a hydrocarbyl orhydrocarbyloxy group having from 1 to about 5 carbon atoms, or ahalogen, such as chlorine or bromine or fluorine and X is ##STR21## orthe acrylate or methacrylate compounds represented by the followingFormula XXXIX ##STR22## wherein R⁴ is a hydrocarbyl group having from 2to about 25 carbon atoms and may be branched, cyclic, polycyclic,saturated or unsaturated and R⁵ is hydrogen or a methyl group.

Typical polymerizable unsaturated monomers represented by FormulaXXXVIII include, for example, styrene, alpha-methylstyrene, o-, m-,p-chlorostyrene: o-, m-, p-bromostyrene; o-, m-, p-tert-butylstyrene;o-, m-, p-methylstyrene; o-, m-, p-methoxystyrene; divinylbenzenes,trivinylbenzenes, o-, M-, p-isopropenylstyrene; o-, m-, p-allylstyrene;o-, m-, p-methallylstyrene; allylbenzene, methallylbenzene,diallylbenzenes and the like.

Typical acrylate (methacrylate) esters represented by Formula XXXIXinclude, for example, ethyl acrylate, n-butyl acrylate, n-butylmethacrylate, secbutyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexylmethacrylate, n-dodecyl acrylate, cyclohexyl acrylate, methylcyclohexylacrylate, norbornyl acrylate, dicyclopentadiene acrylate,methyldicyclopentadiene acrylate and the like.

Other suitable monomers include the acidic monomers, such as acrylic andmethacrylic acid; the amide monomers, such as acrylamide andN-methylacrylamide; the allyl monomers, such as diallylphthalate,triallylisocyanurate, diallylmaleate and dimethallylfumarate; the vinylhalides, such as vinyl chloride and vinyl bromide; the vinyl esters,such as vinyl acetate; the vinyl di and polycyclic aromatics, such asvinyl naphthalene; the vinyl nitriles, such as acrylonitrile; and thehydroxyalkyl acrylates and methacrylates, such as 2-hydroxyethylacrylate.

Compounds Containing Both a Cyanate or Cyanamide Group and aPolymerizable Ethylenically Unsaturated Group for Use in the Curable andCured Compositions

Suitable compounds which contain both a cyanate or cyanamide group and apolymerizable ethylenically unsaturated group in the same molecule thatcan be used to prepare the polymerizable mixtures of the presentinvention include, for example, those represented by the followingFormula XXXX ##STR23## wherein each Y² and R¹ are as hereinbeforedefined, Y⁵ is independently hydrogen, a hydrocarbyl or hydrocarbyloxygroup having from 1 to about 12 carbon atoms, a nitro group, a nitrilegroup, a halogen, such as chlorine or bromine or fluorine, or a --CO--R¹group; or a compound represented by the following Formula XXXXI##STR24## wherein each Y², Y⁵ and R¹ are as hereinbefore defined.

Suitable compounds which contain a cyanate or cyanamide group and apolymerizable ethylenically unsaturated group in the same moleculerepresented by Formulas XXXX and XXXXI include, for example, o-, m-,p-isopropenylphenyl cyanate; o-, m-, p-vinylphenyl cyanate;methyl-p-isopropenylphenyl cyanates; 3-chloro-4-isopropenylphenylcyanate; o-, m-, p-propenylphenyl cyanate; o-, m-, p-allylphenylcyanate; o-, m-, p-methallylphenyl cyanate and the like. Some of thealkenylphenol precursors to the alkenylphenyl cyanates represented byFormula XXXX, notably the vinylphenols, have a tendency to dimerize oroligomerize thus leading to poly(alkenylphenyl)cyanates. It is mostpreferred that the alkenylphenyl cyanate be substantially free ofdimeric and/or oligomeric components, although it is operable to use analkenylphenyl cyanate containing substantial (up to 90 percent byweight) dimeric and/or oligomeric components. A specific preparation ofp-isopropenylphenyl cyanate is taught in Example 1 of U.S. Pat. No.4,559,399 which ia incorporated herein by reference.

Compounds Containing Both a 1,2-Epoxide Group and a PolymerizableEthylenically Unsaturated Group for Use in the Curable and CuredCompositions

Suitable compounds which contain both a 1,2-epoxide group and apolymerizable ethylenically unsaturated group in the same molecule thatcan be used to prepare the polymerizable mixtures of the presentinvention include, for example, those represented by the followingFormulas XXXXII or XXXXIII ##STR25## wherein each Y⁵ and R¹ are ashereinbefore defined.

Suitable compounds which contain a 1,2-epoxide group and a polymerizableethylenically unsaturated group in the same molecule represented byFormulas XXXXII and XXXXIII include, for example, o-, m-,p-isopropenylphenyl glycidyl ether; o-, m-, p-vinylphenyl glycidylether; methyl-p-isopropenylphenyl glycidyl ethers;3-chloro-4-isopropenylphenyl glycidyl ether; o-, m-, p-propenylphenylglycidyl ether; o-, m-, p-allylphenyl glycidyl ether; o-, m-,p-methallyphenyl glycidyl ether and the like. Some of the alkenylphenolprecursors to the alkenylphenyl glycidyl ethers represented by FormulaXXXXII, notably the vinylphenols, have a tendency to dimerize oroligomerize thus leading to poly(alkenylphenyl)glycidyl ethers. It ismost preferred that the alkenylphenyl glycidyl ether be substantiallyfree of dimeric and/or oligomeric components, although it is operable touse an alkenylphenyl glycidyl ether containing substantial (up to 90percent by weight) dimeric and/or oligomeric components. The compoundswhich contain a 1,2-epoxide group and a polymerizable ethylenicallyunsaturated group in the same molecule are prepared using thecorresponding phenol containing a polymerizable ethylenicallyunsaturated group and the hereinbefore described chemistry used in thepreparation of epoxy resins.

Compounds Containing Both a Maleimide Group and a Cyanate Group and noRodlike Mesogenic Structures Suitable for Use in the Curable and CuredCompositions

Suitable compounds which contain both a maleimide group and a cyanategroup in the same molecule and do not contain rodlike mesogenicstructure(s) that can be used to prepare the polymerizable mixtures ofthe present invention include, for example, those represented by thefollowing Formulas XXXXIV or XXXXV ##STR26## wherein each Y⁵, R¹ A" andn are as hereinbefore defined.

Suitable compounds which contain a maleimide group and a cyanate groupin the same molecule and do not contain rodlike mesogenic structuresrepresented by Formulas XXXXIV and XXXXV include, for example,4-(1-(3-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate;4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate;4-(1-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)ethyl)phenylcyanate; 4-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenoxy)phenylcyanate; 4-((4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)thio)phenylcyanate; 4-(4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)benzoyl)phenylcyanate;4-((4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)sulfonyl)phenylcyanate;4-(1-(4-(2,5-dihydro-3-methyl-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate;2,6-dibromo-4-(1-(3,5-dibromo-4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl)-1-methylethyl)phenylcyanate;4-(2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl)phenyl cyanate;3-(2,5-dihydro-2,5 -dioxo-1H-pyrrol-1-yl)phenyl cyanate and the like.Preparation of compounds which contain a maleimide group and a cyanategroup in the same molecule and do not contain rodlike mesogenicstructures is taught in U.S. Pat. No. 4,683,276 which is incorporatedherein by reference.

Compounds Containing One Cyanate or Cyanamide Group Per Molecule and Oneor More Rodlike Mesogenic Moieties which can be Employed in the Curableand Cured Compositions

Suitable compounds which contain one or more rodlike mesogenicstructure(s) and an average of one cyanate or cyanamide group permolecule that can be used to prepare the polymerizable mixtures of thepresent invention include, for example, those represented by thefollowing Formulas XXXXVI, XXXXVII, XXXXVIII or XXXXIX ##STR27## whereinat least 80 percent of the --A-- linkages in Formulas XXXXVI, XXXXVIIand XXXXIX and the direct bond in Formula XXXXVIII and the Y² groups arein the para position with respect to each other and each A, A', A", R,Y², p, n and n' are as hereinbefore defined.

Suitable compounds which contain one or more rodlike mesogenicstructure(s) and an average of one cyanate or cyanamide group permolecule represented by Formulas XXXXVI, XXXXVII, XXXXVIII and XXXXIXinclude, for example, the cyanates of 4-hydroxystilbene,4-hydroxy-4'-methoxystilbene, 4-hydroxy-4'-chlorostilbene,4-hydroxy-4'-nitrostilbene, 4-hydroxy-4'-cyanostilbene,4-hydroxy-alpha-methylstilbene, 4-hydroxychalcone,1-(4-hydroxyphenyl)-2-phenylacetylene,1-(4-hydroxyphenyl)-2-phenylazomethine, 4-hydroxyphenylazobenzene,4-hydroxyphenylazoxybenzene, 4-(4-hydroxyphenoxy)diphenyl,4-hydroxydiphenyl, 4-hydroxy-alpha-cyanostilbene,4-hydroxy-alpha-ethylstilbene, 4-hydroxybenzanilide,4-hydroxy-4'-methoxybenzanilide,4-hydroxy-3,3',5,5'-tetramethyl-alpha-methylstilbene,N-methyl-4-hydroxybenzamide, N-phenyl-4-hydroxybenzamide,4-hydroxy-3,3',5,5'-tetrabromo-alpha-methylstilbene,4-hydroxyphenylbenzoate, phenyl-4-hydroxybenzoate, the cyanamides of4-aminostilbene, 4-amino-alpha-methylstilbene, 4-aminobenzanilide, andthe like. The compounds which contain one or more rodlike mesogenicstructure(s) and an average of one cyanate or cyanamide group permolecule are prepared using the corresponding monophenol (monoamine)containing one or more rodlike mesogenic structure(s) and thehereinbefore described chemistry used in the preparation of polycyanates(polycyanamides).

Method for Forming the Mixtures of the Present Invention

The mixtures of the present invention can be prepared by directlycombining one or more of the desired component(s) with one or morecyanate functional maleimides containing one or more rodlike mesogenicstructures or by addition of one or more of the desired components toone or more of the cyanate functional maleimides containing one or morerodlike mesogenic structures in increments or stages. When a singlecomponent is to be added to one or more of the cyanate functionalmaleimides containing one or more rodlike mesogenic structures, saidcomponent may be prepolymerized (B-staged) or fully homopolymerized,prior to the addition. When two or more components are to be added toone or more of the cyanate functional maleimides containing one or morerodlike mesogenic structures, said components may be partially ortotally copolymerized or reacted together, prior to the addition.Additionally, when two or more components are to be added to one or moreof the cyanate functional maleimides containing one or more rodlikemesogenic structures, one component may be prepolymerized or fullyhomopolymerized in the presence of the other components, prior to theaddition. It is understood that one or more catalysts or acceleratorsmay be included where desired to facilitate the aforementionedcopolymerization, prepolymerization, homopolymerization or reaction ofone or more specific components.

The mixtures can comprise any amount of the compound or compoundscontaining at least one cyanate group, at least one maleimide group andat least one rodlike mesogenic moiety and the other component orcomponents; however, the mixtures suitably contain from about 1 to about99, more suitably from about 99 to about 40, most suitably from about 95to about 70, percent by weight of the compound or compounds containingat least one cyanate group, at least one maleimide group and at leastone rodlike mesogenic moiety and suitably from about 99 to about 1, moresuitably from about 60 to about 1, most suitably from about 30 to about5, percent by weight of the other component or components.

Polymerization (Curing) of the Polymerizable Mixtures

The mixtures of the present invention may be polymerized by heating fromabout 50° C. to about 400° C., preferably by heating from 100° C. to250° C., optionally in the presence of one or more suitable catalysts.For the mixtures containing of one or more of the cyanate functionalmaleimides containing one or more rodlike mesogenic structures, wheneverone or more polymaleimides, compounds containing one or morepolymerizable ethylenically unsaturated group(s), compounds whichsimultaneously contain both a cyanate group or cyanamide group and apolymerizable ethylenically unsaturated group, compounds whichsimultaneously contain both a 1,2-epoxide group and a polymerizableethylenically unsaturated group or compounds which simultaneouslycontain both a maleimide group and a cyanate group and no rodlikemesogenic structures are present, it is often desirable to utilize oneor more free radical forming catalysts for the purpose of polymerizingall or a part of said unsaturated groups. Said free radical formingcatalysts include the organic peroxides and hydroperoxides as well asthe azo and diazo compounds. Preferred free radical forming catalystsinclude benzoylperoxide, t-butylhydroperoxide, t-butylperoxybenzoate,azobisisobutyronitrile, dicumylperoxide, di-tert-butylperoxide andcumene hydroperoxide. The quantity of catalyst used, if any, depends onthe structure of the particular catalyst, the structure of thecomponents used in the polymerizable mixture, the cure structuredesired, the cure time, the cure temperature, and the like. Generally,catalyst concentrations of from about 0.001 to about 2 percent by weightare preferred. B-staging or prepolymerization of the mixtures of thepresent invention can be accomplished by using lower temperatures and/orshorter curing times. Curing of the thus formed B-staged(prepolymerized) mixture can then be accomplished at a later time orimmediately following B-staging (prepolymerization) by increasing thetemperature and/or curing time.

The polymerized (cured) mixtures possess a variety of curing structureswhich depend, in part, upon the amounts and types of individualcomponents used to prepare said mixture, the sequence of componentaddition and procedure used to prepare said mixture, the amounts andtypes of catalysts, if any, employed, the reaction times andtemperatures, and the like.

Mixtures of (A), one or more cyanate functional maleimides containingone or more rodlike mesogenic structures and no other moieties reactivewith the cyanate or maleimide group, and (B-1), one or more polycyanateswhich do not contain rodlike mesogenic structures, and/or (B-3), one ormore polymaleimides and/or prepolymers of any of the aforementionedtypes of compounds, polymerize to produce the aforementioned curingstructures delineated for the (A), cyanate functional maleimidescontaining one or more rodlike mesogenic structures. It should be noted;however, that the relative mole ratio of cyanate groups to maleimidegroups can influence the amounts of the various cure structures in thecured product. For example, a large excess of cyanate groups, providedby using an (B-1) aromatic polycyanate in the copolymerizablecompositions increases the amount of the triazine cure structure in thecured product.

Mixtures of (A), one or more cyanate functional maleimides containingone or more rodlike mesogenic structures and no other moieties reactivewith the cyanate or maleimide group, and (B-2), one or more epoxyresins, polymerize to produce a complex structure, including thatderived from the copolymerization reaction if the cyanate group and theglycidyl ether group ##STR28## Additionally, curing structures derivedfrom homopolymerization of the maleimide groups, homopolymerization ofthe cyanate groups (triazinei, as well as copolymerization of thecyanate and maleimide groups can be present.

Mixtures of (A), one or more cyanate functional maleimides containingone or more rodlike mesogenic structures and no other moieties reactivewith the cyanate or maleimide group, and (B-4), one or more polyamines,polymerize to produce a complex structure including the iminocarbamicacid ester moiety derived from the copolymerization reaction of thecyanate group and the amine group, as well as the addition structurederived from the copolymerization reaction of the amine group and themaleimide unsaturation. Additionally, curing structures derived fromhomopolymerization of the maleimide groups, homopolymerization of thecyanate groups (triazine), as well as copolymerization of the cyanateand maleimide groups can be present.

Mixtures of (A), one or more cyanate functional maleimides containingone or more rodlike mesogenic structures and no other moieties reactivewith the cyanate or maleimide group, and (B-5), one or more polyphenols,polymerize to produce a complex structure including the iminocarbonicacid ester moiety derived from the copolymerization reaction of thecyanate group and the phenolic hydroxyl group, as well as the additionstructure derived from the copolymerization reaction of the phenolichydroxyl group and the maleimide unsaturation. Additionally, curingstructures derived from homopolymerization of the maleimide groups,homopolymerization of the cyanate groups (triazine), as well ascopolymerization of the cyanate and maleimide groups can be present.

Mixtures of (A), one or more cyanate functional maleimides containingone or more rodlike mesogenic structures and no other moieties reactivewith the cyanate or maleimide group, and (B-6), one or morepolymerizable ethylenically unsaturated compounds, polymerize to producea complex curing structure including structure derived from thecopolymerization reaction of the maleimide group and the polymerizableethylenically unsaturated group(s), as well as structure derived fromthe copolymerization reaction of the cyanate group and the polymerizableethylenically unsaturated group(s). Additionally, curing structuresderived from homopolymerization of the polymerizable ethylenicallyunsaturated groups, from homopolymerization of the maleimide groups,from homopolymerization of the cyanate groups (triazine), as well ascopolymerization of the cyanate and maleimide groups can be present.

Mixtures of (A), one or more cyanate functional maleimides containingone or more rodlike mesogenic structures and no other moieties reactivewith the cyanate or maleimide group, and (B-7), one or more compoundswhich simultaneously contain both a cyanate group and a polymerizableethylenically unsaturated group, or (B-8), one or more compounds whichsimultaneously contain both a 1,2-epoxide group and a polymerizableethylenically unsaturated group, or (B-9), one or more compounds whichsimultaneously contain both a maleimide group and a cyanate group anddoes not contain rodlike mesogenic structures, can polymerize to producea complex variety of structures, including those previously mentionedfor the various respective functional groups.

Mixtures of (A), one or more cyanate functional maleimides containingone or more rodlike mesogenic structures, and (B-10), one or morecompounds which contain one or more rodlike mesogenic structures per andonly one cyanate or cyanamide group per molecule, polymerize to producethe aforementioned curing structures delineated for the (A), cyanatefunctional maleimides containing one or more rodlike mesogenicstructures; providing that no other moieties reactive with cyanate ormaleimide groups are present in (A) or (B-10). Increasing the amount ofthe aforementioned cyanate compound containing an average of one cyanategroup per molecule with respect to the amount of cyanate functionalmaleimide can be used as a convenient method for lowering the crosslinkdensity of the thermoset product thereof.

Orientation of the Polymerized Product Containing Rodlike MesogenicStructures

During processing and/or curing of the cyanate functional maleimidescontaining one or more rodlike mesogenic structures or the mixturescontaining said cyanate functional maleimides, electric or magneticfields or drawing and/or shear stresses can be applied for the purposeof orienting the rodlike mesogenic moieties contained or developedtherein. As specific examples of these methods, Finkelmann, et. al.,Macromol. Chem., 180, 803-806 (March, 1979), which is incorporatedherein by reference, induced orientation in an electric field, ofthermotropic methacrylate copolymers containing mesogenic side chaingroups decoupled from the main chain via flexible spacers. Orientationin a magnetic field of mesogenic side chain groups decoupled from themain chain via flexible spacers has been demonstrated by Roth andKruecke, Macromol. Chem., 187, 2655-2662 (November, 1986), which isincorporated herein by reference. Magnetic field induced orientation ofmesogenic main chain containing polymers has been demonstrated by Moore,et. al., ACS Polymeric Material Sciences and Engineering, 52, 84-86(April-May, 1985), which is incorporated herein by reference. Magneticand electric field induced orientation of low molecular weight mesogeniccompounds is discussed by W. Krigbaum in Polymer Liquid Crystals, pages275-309 (1982), published by Academic Press, Inc., which is incorporatedherein by reference. The use of shear to induce orientation is alsodiscussed therein. When the curing is to be performed in an electric ormagnetic field, it is frequently of value to conduct simple preliminaryexperiments that allow for balancing of cure kinetics versus inductionof orientation under the particular experimental conditions beingemployed (i.e. catalyst(s) level being used, temperature used, inherentdielectric or diamagnetic susceptibility of the specific rodlikemesogenic structure(s) used, and the like). This is done recognizing therelatively greater ease of inducing orientation in low molecular weightmaterials versus polymeric materials containing mesogenic moieties.

In addition to orientation by electric or magnetic fields, the cyanatefunctional maleimides containing one or more rodlike mesogenicstructures or mixtures containing said cyanate functional maleimides canbe oriented by drawing and/or shear forces which are induced by flowthrough dies, orifices and mold gates. A general discussion oforientation of thermotropic liquid crystalline polymers by this methodis given by S. K. Garg and S. Kenig in High Modulus Polymers, pages71-103 (1988) published by Marcel Dekker, Inc., which is incorporatedherein by reference. For the mesomorphic cyanate functional maleimidesor mixtures containing said cyanate functional maleimides, this drawingand/or shear orientation can conveniently be produced by or duringprocessing methods such as injection molding, extrusion, pultrusion,filament winding, filming and prepreging.

Other Components which can be Employed

The cyanate functional maleimides containing one or more rodlikemesogenic structures or mixtures containing said cyanate functionalmaleimides can be blended with other materials such as solvents ordiluents, fillers including those comprising a liquid crystallinepolymer, pigments, dyes, flow modifiers, thickeners, reinforcing agents,mold release agents, wetting agents, stabilizers, fire retardant agents,surfactants, low profile additives, shrinkage control agents, otherresinous products, combinations thereof and the like.

These additives are added in functionally equivalent amounts, e.g., thepigments and/or dyes are added in quantities which will provide thecomposition with the desired color; however, they are suitably employedin amounts of from about zero to about 20, more suitably from about 0.5to about 5, most suitably from about 0.5 to about 3 percent by weightbased on the total weight of the composition.

Solvents or diluents which can be employed herein include, for example,hydrocarbons, ketones, aliphatic ethers, cyclic ethers, esters,chlorinated hydrocarbons, combinations thereof and the like.Particularly suitable solvents or diluents include, for example,toluene, xylenes, methylethyl ketone, methylisobutyl ketone, methylamylketone, chloroform, acetone, perchloroethylene, methylene chloride,tetrahydrofuran, 1,4-dioxane, ethyl acetate, butyl acetate, combinationsthereof and the like.

The modifiers such as thickeners, flow modifiers, shrinkage controlagents, low profile additives and the like can be suitably employed inamounts from about 0.05 to about 15, more suitably from about 0.1 toabout 10, most suitably from about 0.1 to about 5 percent by weightbased on the total weight of the composition.

Reinforcing materials which can be employed herein include natural andsynthetic fibers in the form of woven fabric, mats, monofilament,multifilament, unidirectional fibers, rovings, random fibers orfilaments, inorganic fillers or whiskers, hollow spheres, and the like.Suitable reinforcing materials include glass, ceramics, nylon, rayon,cotton, aramid, graphite, polyalkylene terephthlates, polyethylene.polypropylene, polyesters, carbon, boron, asbestos, combinations andhybrids thereof and the like.

Suitable fillers which can be employed herein include, for example,inorganic oxides, ceramic microspheres, plastic microspheres, glassmicrospheres, inorganic whiskers, calcium carbonate, graphite powder,sand, metal powders, combinations thereof and the like. The fillers canbe employed in amounts from about 0.1 to about 95, more suitably fromabout 5 to about 80, most suitably from about 10 to about 50 percent byweight of the total composition.

Uses for the Compositions

The compositions of the present invention can be employed in thepreparation of laminates, prepregs, composites, coatings, castings,pultruded products, filament wound products, films, molding and pottingformulations, injection molded products, and the like.

The following examples are illustrative of the invention but are not tobe construed as to limiting the scope thereof in any manner.

EXAMPLE 1 A. Synthesis of 4-Hydroxy-4'-nitrobenzanilide

p-Hydroxybenzoic acid (59.05 grams, 0.4275 mole), sodium ethoxidecatalyst (0.133 gram, 0.225% wt. of the p-hydroxybenzoic acid used) andN,N'-dimethylacetamide solvent (404 grams) are added to a reactorequipped with a reflux condenser and stirred under a nitrogen atmosphereat 80° C. p-Nitrophenylisocyanate (73.85 grams, 0.450 mole) is initiallyadded in an aliquot of 25.00 grams, followed by 25.00 and 23-85 gramaliquots eleven then nine minutes later, respectively, and so as tomaintain a 80° to 82° C. reaction temperature. After the last aliquot ofp-nitrophenylisocyanate is added, heating of the reactor commenced and a160° C. reaction temperature is achieved 24 minutes later. After threehours at the 160° C. reaction temperature, the reactor is cooled to 30°C. then the contents poured into one gallon of deionized water. Aprecipitated yellow powder is recovered via filtration of the aqueousslurry then dissolved into 1900 milliliters of boiling methanol andrefluxed therein (65° C.). After cooling the methanol solution to 5° C.and maintaining therein for twelve hours, a first crop of pale yellowcolored crystalline product is filtered off and dried at 110° C. undervacuum to a constant weight of 92.5 grams (79.6% isolated yield). Noattempt was made to recover a second crop of crystalline product fromthe mother liquor. Fourier transform infrared spectrophotometricanalysis of a nujol mull of a portion of the product on a sodiumchloride plate revealed the presence of the expected secondary amideN--H stretching (solid state) at 3385 cm⁻¹ (sharp), the secondary amidecarbonyl stretching (solid state) at 1655 cm⁻¹ (sharp), the hydroxylgroup O--H stretching centered at 3232 cm⁻¹ (broad) and the conjugatednitro group absorbances at 1537 and 1339 cm⁻¹ (sharp). Proton magneticresonance spectroscopy (250 MHz) further confirmed the product structureas -hydroxy-4'-nitrobenzanilide.

B. Synthesis of 4-Hydroxy-4'-aminobenzanilide

A portion (44.1 grams, 0.1708 mole) of 4-hydroxy-4'-nitrobenzanilidefrom A. above and ethanol (300 milliliters) are added to a 400milliliter heavy walled glass bottle then sparged with nitrogen. Afterremoval of air by nitrogen sparaing, Raney nickel catalyst (5.5 grams ofa 75% wt. slurry in water at pH 10) is added to the slurry in the glassbottle which is then stoppered and multiply purged with hydrogen toreplace the nitrogen atmosphere. The bottle is then placed on a shakingtype agitator, and pressurized to 48 psig hydrogen. Shaking of thepressurized slurry at room temperature (25° C.) commences until 23.3hours later, the hydrogen pressure reading indicates that 47 psig ofhydrogen has been consumed. By the completion of the hydrogenation, thelight yellow colored reactant slurry became a light pink tan coloredproduct slurry. The product slurry is recovered, diluted intodimethylsulfoxide (300 milliliters) to provide a solution of productcontaining precipitated Raney nickel, then filtered through a mediumporosity fritted glass funnel. The recovered dimethylsulfoxide productsolution is rotary evaporated at 130° C. under vacuum to provide apowder product. The powder product is further dried at 120° C. undervacuum to a constant weight of 8.94 grams (99.88% isolated yield).Fourier transform infrared spectrophotometric analysis of a nujol mullof a portion of the product on a sodium chloride plate the presence ofabsorbances at 3376 (shoulder), 3351 (shoulder), 3316 (sharp) and 3282(shoulder) cm⁻¹ due to secondary amide group N--H stretching (solidstate), primary amine N--H group stretching and hydroxyl group O--Hstretching; the secondary amide carbonyl stretching (solid state) at1645 cm⁻¹ (sharp); and complete disappearance of the conjugated nitrogroup absorbances at 1537 and 1339 cm⁻¹ (sharp). Proton magneticresonance spectroscopy (250 MHz) further confirmed the product structureas 4-hydroxy-4'aminobenzanilide.

C. Synthesis of Monomaleimide of 4-Hydroxy-4'-aminobenzanilide

A portion (38.50 grams, 0.1687 mole) of 4-hydroxy-4'-aminobenzanilidefrom B. above and dry acetic acid (800 milliliters) are added to areactor and maintained under a nitrogen atmosphere with stirring. Thestirred slurry is maintained at 25° C. while maleic anhydride (16.54grams, 0.1687 mole) dissolved in dry acetic acid (100 milliliters) isadded to the reactor. One minute after the addition, a maximum exothermof 27° C. is achieved, then heating is started. Fifty nine minuteslater, the slurry reaches a reaction temperature of 110° C. and ismaintained therein for fourteen hours. The recovered product slurry isrotary evaporated at 80° C. under vacuum to provide a powder product.The powder product is then added to refluxing acetone (500 milliliters)and stirred therein as a slurry for five minutes. After cooling theacetone slurry to room temperature (25° C.), the first crop of lightyellow green colored product is filtered off and dried at 80° C. undervacuum to a constant weight of 43.87 grams (84.38% isolated yield). Noattempt was made to recover a second crop of product the mother liquor.Fourier transform infrared spectrophotometric analysis of a nujol mullof a portion of the product on a sodium chloride plate revealed thepresence of absorbances at 3349 (sharp), 3289 (sharp) and 3087 (broad)cm⁻¹ due to secondary amide group N--H stretching (solid state),hydroxyl group O--H stretching; the secondary amide carbonyl stretching(solid state) at 1649 cm⁻¹ (sharp); and the maleimide carbonyl groupstretching at 1702 cm⁻¹ (sharp). Proton magnetic resonance spectroscopy(250 MHz) further confirmed the product structure as the maleimide of4-hydroxy-4'-aminobenzanilide.

D. Synthesis of the Cyanate of 4-Hydrox-,y-4'aminobenzanilide Maleimide

A portion (10-30 grams, 0.0334 mole) of the maleimide of4-hydroxy-4'-aminobenzanilide from C. above, cyanogen bromide (3-72grams, 0.0351 mole) and acetone (400 milliliters) are added to a reactorand maintained under a nitrogen atmosphere with stirring. The stirredslurry is cooled to -3° C., then triethylamine (3.40 grams, 0.0336 mole)is added to the reactor over a 10 minute period and so as to maintainthe reaction temperature at -3 to -1° C. After completion of thetriethylamine addition, the reactor is maintained at -3° to -1° C. foran additional 35 minutes followed by addition of the reactor contents todeionized water (2000 milliliters). After five minutes, the water andproduct mixture is multiply extracted with three 500 milliliter volumesof methylene chloride. The combined methylene chloride extract is washedwith three 250 milliliter portions of deionized water, then dried overanhydrous sodium sulfate. The dry methylene chloride extract is filteredand solvent removed by rotary evaporation under a vacuum at 60° C. toprovide a powder product. The remaining precipitated product notrecovered by the methylene chloride extractions is directly filtered offthen washed with two 250 milliliter portions of deionized water. Afterdrying under vacuum at 65° C., a constant weight of 3.00 and 6.61 gramsof light yellow colored powder is recovered from the methylene chlorideextraction and the precipitation/filtration, respectively (86.31%isolated yield for the combined product). Fourier transform infraredspectrophotometric analysis of a nujol mull of a portion of the producton a sodium chloride plate revealed the presence of the expectedsecondary amide group N--H stretching (solid state) at 3348 cm⁻¹(sharp), the secondary amide group carbonyl stretching (solid state) at1659 cm⁻¹ (sharp), the maleimide group carbonyl stretching at 1706 cm⁻¹(sharp) and the cyanate group absorbance at 2264 and 2242 cm⁻¹ (sharp)(the analysis was essentially identical for both product fractions).Proton magnetic resonance spectroscopy (250 MHz) further confirmed theproduct structure as the cyanate of 4-hydroxy-4'-aminobenzanilidemaleimide.

E. Characterization of the Cyanate of 4-Hydroxy-4'-aminobenzanilideMaleimide for Liquid Crystallinity

A portion (9.00 milligrams) of the cyanate of4-hydroxy-4'-aminobenzanilide maleimide from D. above is analyzed bydifferential scanning calorimetry using a heating rate of 10° C. perminute under a stream of nitrogen flowing at 35 cubic centimeters perminute and the indicated temperature ranges. The following results wereobtained:

    ______________________________________                                                 OBSERVED                                                                      TRANSITION                                                           CYCLE    TEMPERATURES  EN-                                                    DESIGNA- (°C.)  THALPY                                                 TION     midpoint/range                                                                              (J/g)     COMMENTS                                     ______________________________________                                        First    197/140-214   141.8     Single peak                                  heating                          exotherm                                     (30 to   269/219-366   169.1     Single peak                                  375° C.)                  exotherm                                     ______________________________________                                    

A repeat of the above first heating using a fresh sample (8.20milligrams) and a range of 30° to 300° C. revealed a 273° C. midpointfor the second exothermic peak without a return to baseline by the 300°C. end of the analysis. A second heating of this second sample from 30°to 300° C. revealed only a slight and gradual exothermic shift of thebaseline starting at 258° C.

The cured products are recovered from the differential scanningcalorimetry as golden brown colored solids and are used to prepare nujolmulls. Fourier transform infrared spectrophotometric analysis of a filmof the nujol mulls on a sodium chloride plate revealed that completedisappearance of the cyanate absorbance has occurred with retention ofthe secondary amide group carbonyl stretching (solid state) at 1653 cm⁻¹(sharp) and the maleimide group carbonyl stretching at 1706 cm⁻¹(sharp). The ratio of the amide group N--H absorbance to the amide groupcarbonyl group absorbance for both the cured product and the uncuredproduct (from D. above) is found to be identical, hence substantialretention of the secondary amide group N--H stretching (3348 cm⁻¹) isimplied. The appearance of a new absorbance at 1565 cm⁻¹ is observed inthe cured product. The cured products from both of the differentialscanning analysis gave essentially identical infrared spectrophotometricanalysis.

Analysis of the maleimide cyanate via cross polarized light microscopyis completed using a microscope equipped with a programmable hot stageusing a heating rate of 10° C. per minute and 35×magnification. Thefollowing results are obtained:

    ______________________________________                                                   OBSERVED                                                                      TRANSITION                                                         CYCLE      TEMPERATURES                                                       DESIGNATION                                                                              (°C.)    COMMENTS                                           ______________________________________                                        First       25             Immobile crystals.                                 heating    196             First fluidity noted                                                          as birefringent                                                               nematic droplets.                                             227             Viscosity increasing,                                                         forms birefringent                                                            streaks in shear                                                              direction as sheared.                                         239             Cures to a                                                                    birefringent solid.                                ______________________________________                                    

COMPARATIVE EXPERIMENT A 1. Synthesis of the Cyanate of 3-AminophenolMaleimide

A portion (11.45 grams, 0.0605 mole) of the maleimide of 3-aminophenolprepared using the method of U.S. Pat. No. 4,683,276, Example 1-A,cyanogen bromide (6.73 grams, 0.0636 mole) and acetone (300 milliliters)are added to a reactor and maintained under a nitrogen atmosphere withstirring. The stirred solution is cooled to -5° C., then triethylamine(6.16 grams, 0.0608 mole) is added to the reactor over a 10 minuteperiod and so as to maintain the reaction temperature at -5° to -1° C.After completion of the triethylamine addition, the reactor ismaintained at -3° to -1° C. for an additional 35 minutes followed byaddition of the reactor contents to deionized water (1500 milliliters).After five minutes, the water and product mixture is multiply extractedwith three 200 milliliter volumes of methylene chloride. The combinedmethylene chloride extract is washed with three 250 milliliter portionsof deionized water, then dried over anhydrous sodium sulfate. The drymethylene chloride extract is filtered and solvent removed by rotaryevaporation under a vacuum at 60° C. to provide a powder product. Afterdrying under vacuum at 65° C., a constant weight of 11.08 grams lighttan colored powder is recovered (85.47% isolated yield). Fouriertransform infrared spectrophotometric analysis of a neat film of aportion of the product on a sodium chloride plate revealed the presenceof the expected maleimide group carbonyl stretching at 1716 cm^(-`)(sharp) and the cyanate group absorbance 2265 and 2234 cm⁻¹ (sharp).Proton magnetic resonance spectroscopy (250 MHz) further confirmed theproduct structure as the cyanate of 4-aminophenol maleimide.

2. Characterization of the Cyanate of 3-Aminophenol Maleimide for LiquidCrystallinity

Results of the analysis of the cyanate of 3-aminophenol maleimide bydifferential scanning calorimetry are reported in U.S. Pat. No.4,680,378, Comparative Experiment A. Analysis of the maleimide cyanateusing cross polarized light microscopy as per the method of Example 1-Eabove demonstrated that the product became fluid upon heating withoutany birefringence. Shearing of the fluid produced no birefringence, andthe product cured to a nonbirefringent solid.

EXAMPLE 2 A. Preparation and Curing of a Blend of the Cyanate of4-Hydroxy-4'-aminobenzanilide Maleimide and Bisphenol A Dicyanate

A portion (2.35 grams, 25% wt.) of the cyanate of4-hydroxy-4'-aminobenzanilide maleimide from Example 1-D and bisphenol Adicyanate (7.05 grams, 75% wt.) are ground together to form ahomogeneous powder blend. A portion (5.0 grams) of the resultant blendis heated to 125° C. to provide a homogeneous paste which is thencatalyzed by vigorously mixing in cobalt naphthenate (6.0 percentactive) (0.005 grams, 0.10% wt.) dissolved in methylene chloride (0.30milliliter). The catalyzed blend is then placed in an oven which ispreheated to 140° C. and held for ten minutes at this temperature. Themolten blend is removed, degassed in a vacuum bell jar, then poured intothe reservoir of an injection molder preheated to 140° C. Blendremaining after filling of the reservoir was poured into an aluminumdish and placed back into the 140° C. oven. After 10 minutes in thereservoir, the blend is injected through a 0.0625 inch square orificeinto a mold preheated to 140° C. and having the following dimensions:3.0 by 0.5 by 0.125 inches. The filled mold is immediately transferredto the 140° C. oven which also contains the blend in the aluminum dish.Heating of both the mold and the aluminum dish to 177° C. commences andthis temperature is then maintained for 2 hours. The oven temperature isthen increased to 200° C. and maintained therein for 2 hours followed byincreasing to 240° C. After 2 hours at the 240° C. temperature, the ovenis slowly cooled to room temperature (25° C.) then the casting isrecovered from the mold and the film is recovered from the aluminumdish.

B. Dynamic Mechanical Analysis and Thermal Mechanical Analysis of theCured Blend

Dynamic mechanical analysis of the molded cured blend is completed usinga heating rate of 5° C. per minute and a range of 30° C. to 300° C. Thetensile storage modulus measured at 40°, 80°, 120°, 160° and 200° C. isreported in Table I. Thermal mechanical analysis of the film of thecured blend is completed with glass transition temperature and the meanlinear thermal coefficient of expansion over the range of 30° C. to Tgevaluated. In this analysis, a constant probe force of 0.1 Newtons and aheating rate of 10° C. per minute is used over a range of 25° C. to 330°C. The results are reported in Table I.

COMPARATIVE EXPERIMENT B 1. Preparation and Curing of a Blend of theCyanate of 3-Aminophenol Maleimide and Bisphenol A Dicyanate

A portion (9.40 grams, 25% wt.) of the cyanate of 3-aminophenolmaleimide from Comparative Experiment A-1 and bisphenol A dicyanate(28.20 grams, 75% wt.) are ground together to form a homogeneous powderblend. A portion (5.0 grams) of the resultant blend is heated to 125° C.to provide a homogeneous paste which is then catalyzed by vigorouslymixing in cobalt naphthenate (6.0 percent active) (0.005 grams, 0.10%wt.) dissolved in methylene chloride (0-30 milliliter). The catalyzedblend is then used to prepare a molded test piece and a film using themethod of Example 2-A.

2. Dynamic Mechanical Analysis and Thermal Mechanical Analysis of theCured Blend

Dynamic mechanical analysis of the molded cured blend is completed usingthe method of Example 2-B. Thermal mechanical analysis of the film ofthe cured blend is completed with glass transition temperature and themean linear thermal coefficient of expansion over the range of 30° C. toTg evaluated using the method of Example 2. The results are reported inTable I.

                  TABLE I                                                         ______________________________________                                                         DESIGNATION                                                                   OF SAMPLE                                                                    EXAMPLE    COMP.                                                              2          EXPT. B*                                           ______________________________________                                        Dynamic Mechanical Analysis:                                                  Tensile Storage Modulus (GPa)                                                  40° C.    1.430        0.877                                           80° C.    1.284        0.826                                          120° C.    1.220        0.770                                          160° C.    1.146        0.726                                          200° C.    1.022        0.634                                          Thermal Mechanical Analysis:                                                  Tg (°C.)   228.5        202.8                                          Mean linear Coefficient of                                                                      48           63                                             Thermal Expansion (ppm/°K.)                                            ______________________________________                                         *Not an example of the present invention.                                

EXAMPLE 3 A. Synthesis of a-p-Nitrophenyl-p-acetoxycinnamic Acid

p-Nitrophenylacetic acid (94.02 grams, 0.519 mole) and 1.038 N sodiumhydroxide solution (500 mL) are added to a 1,000 mL beaker and heatedwith stirring to 60° C. The resultant solution is rotary evaporatedunder vacuum until final conditions of 110° C. and 1 mm Hg are achievedand maintained for 30 minutes. A portion (101.6 grams, 0.50 mole) of theresultant dry white carboxylic acid sodium salt, p-hydroxybenzaldehyde(61.06 grams, 0.50 mole) and acetic anhydride (250 grams) are added to areactor equipped with a reflux condenser and stirred under a nitrogenatmosphere at a 147° C. reflux. Refluxing continued over the next twentyhours at which time the temperature has increased to 159° C. At thistime, the reactor is cooled to 100° C. and ethanol (300 mL) and water(50 mL) are added. The resultant slurry is boiled at 89° C. for one hourfollowed by cooling to 50 ° C. and filtration. The filtrate is added todeionized water (1500 mL) and the resultant precipitate recovered byfiltration. The precipitate is exhaustively extracted with deionizedwater saturated with sodium carbonate. The combined extracts arefiltered then neutralized with concentrated hydrochloric acid inducingformation of a precipitate. The precipitate is recovered by filtrationthen dried at 50° C. in a forced air convection type oven. The drypowder is added to a beaker along with carbon tetrachloride (200 mL)then stirred with heating to a boil. Acetic acid (40 mL) is added to theboiling slurry then heating back to a boil resumed. After boiling isachieved, the slurry is maintained at 4° C. for 15 hours. Theprecipitate is recovered by filtration and dried at 70° C. under avacuum of 5 mm Hg to a constant weight of 38.55 grams of brilliant lightyellow colored crystalline powder.

B. Synthesis of 4-Nitro-4'-hydroxystilbene

A portion (36.75 grams) of a-p-nitrophenyl-p-acetoxycinnamic acid fromA. above, ethanol (300 mL) and concentrated hydrochloric acid (300 mL)are added to a reactor equipped with a reflux condenser and stirredunder a nitrogen atmosphere. Heating commenced and a reflux is achievedat 93° C. Refluxing continued over the next 262 minutes at which timethe temperature has increased to 95° C. At this time, the contents ofthe reactor are poured into deionized water (one liter) and theresultant precipitate recovered by filtration. The wet filter cake iswashed with two portions (500 mL) of deionized water then dissolved instirred ethanol (750 mL) maintained at 82° C. The resultant solution ismaintained at 4° C. for 15 hours. The precipitate is recovered byfiltration and dried at 75° C. under a vacuum of 2 mm Hg to a constantweight of 22.70 grams of light orange colored crystalline needles.Fourier transform infrared spectrophotometric analysis of a potassiumchloride pellet of a portion of the product revealed the presence of theexpected hydroxyl group O--H stretching centered at 3422 cm⁻¹ (broad),conjugated nitro group absorbances at 1516 and 1337 (1317 shoulder) cm⁻¹(sharp) and the ethylene C-H out-of-plane deformation at 972 cm⁻¹.

C. Synthesis of 4-Hydroxy-4'-aminostilbene

A portion (20.9 grams, 0.0866 mole) of 4-nitro-4'-hydroxystilbene fromB. above and ethanol (300 mL) are added to a 400 milliliter heavy walledglass bottle then sparged with nitrogen. After removal of air bynitrogen sparging, Raney nickel catalyst (2.5 grams of a 50% wt. slurryin water at pH 10) is washed one time with ethanol, then added to theslurry in the glass bottle which is then stoppered and multiply purgedwith hydrogen to replace the nitrogen atmosphere. The bottle is thenplaced on a shaking type agitator, and pressurized to 46.5 psig (320.6kPa) hydrogen. Shaking of the pressurized slurry at room temperature(25° C.) commences until 28.5 hours later, the hydrogen pressure readingindicates that 19.6 psig (135.1 kPa) of hydrogen has been consumed. Theproduct slurry is recovered, diluted into dimethylsulfoxide (150 grams)to provide a solution of product containing precipitated Raney nickel,then filtered through a medium porosity fritted glass funnel. Therecovered dimethylsulfoxide product solution is rotary evaporated at130° C. under vacuum to provide a powder product. The powder product isfurther dried at 100° C. under vacuum of 2 mm Hg to a constant weight of18.17 grams (99.25% isolated yield) of orange brown colored powder.Fourier transform infrared spectrophotometric analysis of a potassiumchloride pellet of a portion of the product revealed the presence ofabsorbances at 3363 (sharp) and 3289 cm⁻¹ (sharp) due to primary amineN--H group stretching and hydroxyl group O--H stretching, completedisappearance of the conjugated nitro group absorbances at 1516 and 1337(1317 shoulder) cm⁻¹ (sharp) and the ethylene C--H out-of-planedeformation at 965 cm⁻¹. Nuclear magnetic resonance spectroscopyconfirmed the integrity of the stilbene ethylenic unsaturated structure.

D. Synthesis of Monomaleimide of 4-Hydroxy-4'-aminostilbene

A portion (17.63 grams, 0.0835 mole) of 4-hydroxy-4'-aminostilbene fromC. above, dry acetic acid (500 mL) and maleic anhydride (8.18 grams,0.0835 mole) dissolved in acetic acid (100 grams) are added to a reactorand maintained under a nitrogen atmosphere with stirring. Heatingcommenced and the slurry reaches a reaction temperature of 110° C. andis maintained thereat for fourteen hours. The recovered product slurryis rotary evaporated at 70° C. under vacuum of 1 mm Hg to provide apowder product. The powder product is then added to refluxing acetone(75 mL) and stirred therein as a slurry for five minutes. After coolingthe acetone slurry to room temperature (24° C.), the first crop ofgolden yellow colored product is filtered off and is dried at 70° C.under vacuum to a constant weight of 19.14 grams (78.73% isolatedyield). No attempt is made to recover a second crop of product from themother liquor. Fourier transform infrared spectrophotometric analysis ofa potassium chloride pellet of a portion of the product revealed thepresence of absorbances centered at 3442 cm⁻¹ (broad) due to thehydroxyl group O--H stretching, the maleimide carbonyl group stretchingat 1702 cm⁻¹ (sharp) (1775 cm⁻¹ shoulder) and the ethylene C-Hout-of-plane deformation at 965 cm⁻¹. Differential scanning calorimetryof a portion (10.95 milligrams) of the product using a heating rate of10° C. per minute under a stream of nitrogen flowing at 35 cubiccentimeters per minute and a temperature range of 30° to 375° C.revealed a single exotherm with an onset temperature of 196° C.,midpoint temperature of 254° C., endpoint temperature of 369° C. and anenthalpy of 218 J/g.

E. Synthesis of the Cyanate of 4-Hydroxy-4'-aminostilbene Maleimide

A portion (14.56 grams, 0.05 mole) of the maleimide of4-hydroxy-4'-aminostilbene from D. above, cyanogen bromide (5.56 grams,0.0525 mole) and acetone (1600 mL) are added to a reactor and maintainedunder a nitrogen atmosphere with stirring. The stirred slurry is cooledto -2° C., then triethylamine (5.09 grams, 0.0503 mole) is added to thereactor over a 5 minute period and so as to maintain the reactiontemperature at -2° to -1° C. After completion of the triethylamineaddition, the reactor is maintained at -2° to 0° C. for an additional 40minutes followed by addition of the reactor contents to deionized water(3000 mL). After five minutes, the precipitated product is directlyfiltered off then washed with three 250 mL portions of deionized water.After drying under vacuum of 2 mm Hg at 65° C., a constant weight of15.3 grams of yellow colored powder is recovered (96.74% isolatedyield). Fourier transform infrared spectrophotometric analysis of apotassium chloride pellet of a portion of the product revealed thepresence of the maleimide group carbonyl stretching 1716 cm⁻¹ (sharp)(1775 cm⁻¹ shoulder) and the cyanate group absorbance at 2267 and 2234cm⁻¹ (sharp) and the ethylene C--H out-of-plane deformation at 965 cm⁻¹.

F. Characterization of the Cyanate of 4-Hydroxy-4'-aminostilbeneMaleimide for Liquid Crystallinity

A portion (10.43 milligrams) of the cyanate of4-hydroxy-4'-aminostilbene maleimide from E. above is analyzed bydifferential scanning calorimetry using a heating rate of 10° C. perminute under a stream of nitrogen flowing at 35 cubic centimeters perminute and the indicated temperature ranges. The following results areobtained:

    ______________________________________                                                  Observed                                                                      Transition                                                                    Temperatures                                                                  (°C.)                                                        Cycle     midpoint/    Enthalpy                                               Designation                                                                             range        (J/g)    Comments                                      ______________________________________                                        First     168 and      510.7    Pair of                                       Heating   295/79-371            exotherms                                     (30 to                          which                                         375° C.)                 merge.                                        ______________________________________                                    

The cured product is recovered from the differential scanningcalorimetry as a brown colored solid and is used to prepare a potassiumchloride pellet. Fourier transform infrared spectrophotometric analysisrevealed that complete disappearance of the cyanate absorbance hasoccurred with retention of the maleimide group carbonyl stretching at1702 cm⁻¹ (sharp) 1769 cm⁻¹ shoulder) and the ethylene C--H out-of-planedeformation at 965 cm⁻¹. The appearance of a new absorbance at 1565 cm⁻¹is observed in the cured product.

Analysis of the maleimide cyanate via cross-polarized light microscopyis completed using a microscope equipped with a programmable hot stageusing a heating rate of 10° C. per minute and 35× magnification. Thefollowing results are obtained:

    ______________________________________                                                Observed Transition                                                   Cycle   Temperatures (°C.)                                             Designation                                                                           midpoint/range Comments                                               ______________________________________                                        First    25            Immobile crystals.                                     Heating                                                                               144            First fluidity noted with                                                     birefringent nematic texture                                                  when compressed between                                                       slide and coverslip.                                           154            Birefringent nematic fluid.                                    202            Birefringent nematic fluid                                                    with increasing viscosity.                                     212            Cures to a birefringent solid.                         ______________________________________                                    

EXAMPLE 4 Preparation of a Cured Casting of the Cyanate of4-Hydroxy-4'-aminostilbene Maleimide

A portion (1.016 grams) of the cyanate of 4-hydroxy-4'-aminostilbenemaleimide from Example 3-E is placed in an aluminum pan. The aluminumpan is then placed in a forced air convection type oven which has beenpreheated to 180° C. Within the first five minutes in the oven, melt isobserved followed by thermosetting. After two hours at 180° C., the oventemperature is increased 20° C. every two hours to a final temperatureof 240° C. After four hours at the 240° C. temperature, the oven isallowed to slowly cool to room temperature (24° C.) . Once at roomtemperature, the casting is removed from the pan and examined bycrosspolarized light microscopy at 70×magnification. A high level ofbirefringence is observed in the cured product. A portion (25milligrams) of the casting is analyzed by differential scanningcalorimetry using a heating rate of 10° C. per minute under a stream ofnitrogen flowing at 35 cubic centimeters per minute and a temperaturerange of 30° to 300° C. In this analysis, no glass transitiontemperature is observed to 270° C. where a rise in heat flow occurs.

What is claimed is:
 1. A product resulting from curing a compoundcontaining at least one cyanate group, at least one maleimide group andat least one rodlike mesogenic moiety, wherein at least 80 percent ofsaid cyanate groups and maleimide groups are in the para position withrespect to the rodlike mesogenic moiety wherein the compound being curedis represented by the following Formulas I, II, III or IV ##STR29##wherein at least about 80 percent of the --A-- linkages in Formulas I,II and IV and the direct bond in Formula III and the Y groups are in thepara position with respect to each other; one Y group is a cyanate,--O--C.tbd.N, group and the other Y group is a maleimide grouprepresented by the formula ##STR30## each A is independently --CR¹ ═CR¹--, --C.tbd.C--, --N═N--, --CR¹ ═N--, --O--CO--, --NR¹ --CO--, --CR¹═N--N═CR¹ --, --CR¹ ═CR¹ --CO--, --CO--O--, --CO--NR¹ --, --CO--CR¹ ═CR¹--, --CR¹ ═CR¹ --O--CO--(CH₂)_(n') --, --N═CR¹ --, --(CH₂)_(n')--CO--O--CR¹ ═CR¹ --, --CR¹ ═CR¹ --O--CO--, --CO--O--CR¹ ═CR¹ --,--CO--O--N═CR¹ --, --CR¹ ═N--O--CO--, --CR¹ ═CR¹ --CO--O--, --CO--S--,--O--CO--CR¹ ═CR¹ --, --CR¹ ═CR¹ --CO--O--(CH₂)_(n') --, --S--CO--,--(CH₂)_(n') --O--CO--CR¹ ═CR¹ --, --CHR¹ --CHR¹ --CO--O--,--O--CO--CHR¹ --CHR¹ --, --C.tbd.C--C.tbd.C--, --CR¹ ═CR¹ --CR¹ ═CR¹ --,--CO--NR¹ --NR¹ --CO--, ##STR31## A' is a divalent hydrocarbyl grouphaving from 1 to about 10 carbon atoms; each A" is independently analkylene group having from 1 to about 10 carbon atoms carbon atoms, adirect bond, --O--, --CO--, --S--, --S--SO--, --SO--, --SO₂ -- or--O--CO--O--; each A¹ is independently a --CO--, --O--CO--, --CO--O--,--CO--NR¹ --, or --NR¹ --CO-- group; each R is independently hydrogen ora hydrocarbyl or hydrocarbyloxy group having from 1 to about 10 carbonatoms, a halogen atom, a nitro group, a nitrile group, a phenyl group ora --CO--R¹ group; each R¹ is independently hydrogen or a hydrocarbylgroup having 1 to about 3 carbon atoms; n has a value of zero or 1; n'has an average value from zero to about 6; and p has an average valuefrom 1 to about 30; with the proviso that any of the aromatic rings can,if desired, contain a nitrogen, oxygen or sulfur heteroatom.
 2. Aproduct of claim 1 wherein A' has from 1 to about 4 carbon atoms; whenA" is an alkylene group, it has from 1 to about 4 carbon atoms; each Ris independently hydrogen or a hydrocarbyl group having from 1 to about4 carbon atoms, chlorine or bromine; n' has an average value from zeroto about
 3. 3. A product of claim 1 wherein the compound that is curedis selected from the group consisting of ##STR32## V¹ is a maleimidegroup represented by the formula ##STR33## and V is a cyanate group,--O--C.tbd.N, and where R¹ is independently hydrogen or a hydrocarbylgroup having 1 to about 3 carbon atoms.
 4. The product of claim 1, 2, or3 wherein the compound or compounds containing the rodlike mesogenicmoieties are oriented prior to curing or during curing or both prior toand during curing.
 5. The product of claim 4 wherein said orientation isaccomplished by use of an electric or magnetic field or by drawing orshear forces or any combination thereof.